Water collection trough assemblies are used in the heat exchanger industry in counter flow cooling towers to collect and remove water falling from the bottom of a cooling tower fill or from a heat exchanger tube bundle.
Forced draught cooling towers require water collection trough assemblies in order to collect water falling from the fill of the cooling tower or other water cooling facility to enable the water to be recycled or disposed of in an effective way.
Collecting troughs are used in forced draught cooling towers; in cooling towers where the rain zone is eliminated to reduce pumping power; in counter-flow cooling tower fill test facilities; and in deluged evaporative heat exchangers, to collect and remove water dripping from the base of the cooling tower fills or heat exchanger tube bundles while allowing it to pass vertically through them.
Effective recovery of the water also reduces damage to, and maintenance of, fans and drives which create air flow through a heat exchange facility.
Inefficient recovery of water can also result in increased power consumption and water spillage, which has a negative environmental impact due to the contaminants in the water.
Numerous different water collection assemblies have been developed some of which have fairly complicated geometries. Some of them unduly increase the pressure drop of air flowing upwards and thereby increase power consumed by one or more fans inducing the flow of air.
Some water collection assemblies have multiple parallel troughs extending in one direction beneath the fill of a cooling tower or tube bundle with an upwardly inclined capture plate having its lower edge arranged to feed water falling onto the capture plate into an associated trough. The troughs and capture plates are arranged to extend over substantially the entire area beneath the fill or tube bundle, as the case may be, so that all water that drips from the fill or tube bundle falls onto a capture plate or directly into a trough. U.S. Pat. No. 4,521,350 describes such an arrangement.
The difficulty with this arrangement is that water drops falling on the capture plate tend to splash and at least a part of the resultant spray can find its way between the troughs thereby failing to be caught by the trough and capture plate assembly. This has led, in at least some instances, to a second layer of collection troughs and capture plates being located beneath a first one.
Measurements done on an existing collection trough assembly comprising two layers of troughs installed in a cooling tower fill test facility have shown that about 10% of the water passes through the first layer of troughs.
In dephlegmators of the type used in steam condensation installations operated in a wet, evaporatively cooled mode, collection trough assemblies may be provided beneath tube bundles in order to collect run-off water and enable recycling of excess deluge water.
There is a need for a water collection trough assembly that alleviates some of the problems mentioned above, at least to some extent.